Abstract: A communication system connects stationary and second entities via a cellular radio intermediate network. Each such entity has its own network that is separate from the intermediate network, and connects to the intermediate network by a gateway device. A gateway transfers a message while executing protocol conversion under interpretation of a message header. The conversion maintains in the header at least a predetermined subset of the following: Source Address, Geographic Address, Priority Level, Reliability Level, Delay Requirement, Expiry Time and Repetition Time. A critical distinction exists between connectionless and connection-oriented service.

Abstract: In a method of data transmission from a plurality of sub-stations to a main station over a common channel which is subdivided into time slots whose length and synchronization are determined by a corresponding time slot distribution of a data transmission signal sent out by the main station, in which each sub-station has a predetermined probability p of transmitting a data packet in each time slot, the throughput of the communication channel is improved in that if the main station has correctly received in a specific time slot (n) a data packet coming from a specific sub-station, always a next time slot (n+j) will be reserved to be exclusively used by that specific sub-station.

Abstract: For locating an earthbound and freely movable vehicle, first interfacing to an external coordinate system for determining an actual vehicle position is effected. This position is recurrently and wireless transmitted to a remote station. For restricting the number of transmissions in the vehicle a discrete internal change of status is detected. Upon detection the transmitting is effected.

Abstract: A communication protocol is proposed, to be used by a main station and a plurality of mobile sub-stations, while time slots are used in which data packets are transmitted. A sub-station that has a message to be sent to the main station first transmits a request-for-access data packet to the main station. If the sub-station knows its own position as well as that of the main station, the sub-station applies an advancement of time to the request-for-access data packet, so that this may be longer and contain more information, such as a self-selected recognition code and/or information relating to the length of the message to be sent.The main station measures the instant at which the request-for-access data packet is received relative to the time slot distribution and sends a correction of the advancement of time to the sub-station.

Abstract: Via a cellular radio communication system, measured values are transmitted from vehicles to a computer. The measured values are chosen so that they can be used to determine Origin-Destination matrices without infringing upon the privacy of the users.

Abstract: In a method of data transmission from a plurality of sub-stations to a main station over a common channel which is subdivided into time slots whose length and synchronization are determined by a corresponding time slot distribution of a data transmission signal sent out by the main station, in which each sub-station in each time slot has a predetermined probability p of transmitting a data packet, the throughput of the communication channel is improved in that the probability p is adapted to the load of the communication channel.